JP2017057497A - Aluminum alloy fin material for heat exchanger and method for manufacturing same, and heat exchanger using the aluminum alloy fin material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aluminum alloy fin material for a heat exchanger, excellent in fin melting resistance upon being brazed and exhibiting excellent high temperature durability after being brazed, and a heat exchanger using same.SOLUTION: The aluminum alloy fin material for a heat exchanger is provided which is characterized in that: it contains Si:0.70 to 1.50 mass%, Fe:0.05 to 2.00 mass%, Mn:1.0 to 2.0 mass%, Zn:0.5 to 4.0 mass% and the balance Al with inevitable impurities; and in heating before brazing, the quantity of solid solution Si is 0.60 mass% or less and the quantity of solid solution Mn is 0.60 mass or less and recrystallization temperature in a temperature rising process during brazing is 450°C or less. There are also provided a method for manufacturing the aluminum alloy fin material, a heat exchanger using the aluminum alloy fin material and a method for manufacturing the heat exchanger.SELECTED DRAWING: None

Description

  The present invention relates to an aluminum alloy fin material for a heat exchanger, in particular, a radiator, a heater core, an oil cooler, an intercooler, a car air conditioner condenser, an evaporator, and the like by brazing the fin and the constituent material of the working fluid passage. Aluminum alloy fin material for heat exchanger to be joined, especially aluminum alloy fin material for heat exchanger excellent in fin melting resistance during brazing and high temperature durability after brazing, its production method, and aluminum alloy fin material The present invention relates to an assembled heat exchanger.

  Aluminum alloy is lightweight and has high thermal conductivity, and high corrosion resistance can be realized by appropriate treatment, so it is used for heat exchangers for automobiles, such as radiators, condensers, evaporators, heaters, intercoolers, oil coolers, etc. It has been. As a tube material for an automobile heat exchanger, an Al—Mn alloy such as a 3003 alloy is used as a core material, and an Al—Si alloy brazing material or an Al—Zn alloy sacrificial anode material is provided on one surface thereof. A two-layer tube material clad with an Al—Si alloy brazing material on the other surface is used. The heat exchanger is usually joined by combining such a tube material and a corrugated aluminum alloy fin material and brazing at a high temperature of about 600 ° C.

  In such a heat exchanger, as the aluminum alloy fin material, pure aluminum alloys such as JIS1050 alloy having excellent thermal conductivity, and Al-Mn alloys such as JIS3003 alloy having excellent strength and buckling resistance are generally used. Has been used.

  By the way, in recent years, demands for weight reduction, miniaturization, and high performance have been increasing for heat exchangers. Along with this, the aluminum alloy fin material to be joined by brazing is also thin and has good brazing properties, and excellent properties such as strength, thermal conductivity and corrosion resistance after brazing addition heat. Is particularly desired. However, as the thinning progresses, it has become particularly difficult to solve the following problems.

  One problem is that the fins are eroded by the brazing produced from the Al—Si brazing material during brazing, and the fins melt at the grain boundaries. Since Zn and Si are segregated at the grain boundaries, the concentration of Zn and Si is higher and the melting point is lower than that of the matrix. In addition, during brazing, Si diffuses from the molten braze into the fins. At this time, the diffusion rate of Si at the crystal grain boundary is significantly larger than the diffusion rate of Si in the matrix, and therefore, a large amount of Si is particularly introduced into the grain boundary. Diffuses. Since Si diffuses throughout the fin plate thickness, the effect is not significant if the fin plate thickness is thick, but if the plate thickness is thin, the amount of Si solid solution at the grain boundary of the fin material greatly increases. The melting point of the grain boundary is lowered and the fin is melted. Therefore, it is necessary to reduce the amount of Si solid solution in the fin material before brazing in advance.

  A technique for suppressing the amount of dissolved Si in the fin material is described in Patent Document 1. In this technique, it is said that the intergranular corrosion of fins can be suppressed by setting the Si solid solution amount at the fin thickness center after brazing heat to 0.7% or less. However, this technique is not intended to solve the problem of fin melting at grain boundaries. Therefore, the amount of solid solution Si before brazing and the problem that segregation to the grain boundary influences the fin melting resistance is not recognized at all, and does not suggest any solution. .

  The other is the problem of poor durability at high temperatures. For example, when used as a fin of a radiator, the cooling water flowing inside the tube becomes a high temperature of about 85 to 120 ° C., and the tube is repeatedly swollen by the internal pressure, and the high temperature fatigue damage is given to the fin. Therefore, if the fin plate is thin, it will break due to high temperature fatigue damage.

  A technique for improving the durability of the fin is described in Patent Document 2. In this technique, the strength of the fin material after brazing addition heat is improved by controlling the Al— (Mn, Fe) —Si-based compound to an appropriate number density. As a result, the strength as a heat exchanger, That is, durability is improved. However, in this technique, no mention is made of the fact that the heat exchanger becomes high temperature, and therefore no solution is suggested for the problem of fin breakage due to high temperature fatigue damage.

JP 2004-084060 A JP 2012-126950 A

  Thus, when a thin aluminum alloy fin material is used in a heat exchanger, an aluminum alloy fin material that suppresses melting of fins at grain boundaries during brazing and is excellent in high-temperature durability after brazing is provided. This has been difficult with the prior art.

  The present invention has been completed to solve the above-described problems, and has excellent fin melting resistance during brazing, and has excellent high temperature durability after brazing, and an aluminum alloy fin material for heat exchangers and its It is an object of the present invention to provide a manufacturing method and a heat exchanger for automobiles using the same.

  In the first aspect of the present invention, Si: 0.70 to 1.50 mass%, Fe: 0.05 to 2.00 mass%, Mn: 1.0 to 2.0 mass%, Zn: 0.5 to 4.0 mass %, The balance Al and inevitable impurities are made of an aluminum alloy, the amount of solid solution Si is 0.60 mass% or less and the amount of solid solution Mn is 0.60 mass% or less before brazing heat, The aluminum alloy fin material for heat exchangers was characterized in that the recrystallization temperature in the temperature rising process was 450 ° C. or lower.

  In the second aspect of the present invention, in the first aspect of the present invention, in the aluminum alloy after brazing addition heat, the solid solution Mn amount is 0.60 mass% or less, and the Si and Zn concentrations in the vicinity of the grain boundary are respectively S1 mass% and Z1 mass. %, And the Si and Zn concentrations in the matrix were S2 mass% and Z2 mass%, respectively, the values of S1 / S2 and Z1 / Z2 were both 1.20 or less.

  According to a third aspect of the present invention, in the first or second aspect, the aluminum alloy is Cu: 0.05 to 0.30 mass%, Ti: 0.05 to 0.30 mass%, Zr: 0.05 to 0.30 mass. %, Cr: 0.05 to 0.30 mass%, and V: 0.05 to 0.30 mass%, or one or more selected from 0.05 to 0.30 mass%.

  The manufacturing method according to the first aspect of the aluminum alloy fin material for a heat exchanger of the present invention is the method for manufacturing an aluminum alloy fin material for a heat exchanger according to any one of claims 1 to 3, in claim 4. , A step of casting the aluminum alloy, a hot rolling step of hot rolling the cast ingot, a cold rolling step of cold rolling a hot rolled plate, and a cold rolling step in the middle of the cold rolling step One or more annealing steps for annealing the cold rolled sheet in one or both of the steps, wherein the hot rolling step includes a heating step, a holding step, and a hot rolling step, and in the heating step, 400 The rate of temperature rise from the time of reaching ° C to the time of reaching the holding temperature in the holding stage is 60 ° C / h or less, the holding temperature in the holding stage is 450 to 560 ° C, the holding time is 0.5 hours or more, During the rolling stage, heat An aluminum alloy fin material for a heat exchanger characterized in that the time during which the temperature of the rolled plate is 400 ° C or higher is 5 minutes or longer, and the temperature of the cold rolled plate is 120 ° C or lower in the cold rolling step. It was set as the manufacturing method.

  The manufacturing method which concerns on the 2nd aspect of the aluminum alloy fin material for heat exchangers of this invention is a manufacturing method of the aluminum alloy fin material for heat exchangers as described in any one of Claims 1-3 in Claim 5. , A process of casting the aluminum alloy, a homogenization process of homogenizing the cast ingot, a hot rolling process of hot rolling the homogenized ingot, and cold rolling the hot rolled plate A cold rolling step, and one or more annealing steps for annealing the cold rolled sheet in one or both of the cold rolling step and in the middle of the cold rolling step, and the homogenization step is a heating step A holding stage and a cooling stage, and in the heating stage, the rate of temperature rise from reaching 400 ° C. to reaching the holding temperature in the holding stage is 60 ° C./h or less, and the holding temperature in the holding stage is 450 to 560. ℃ and hold 1.0 hour or more, and during the cooling stage, the cooling rate until the temperature of the ingot reaches 400 ° C. is 60 ° C./h or less. In the cold rolling step, the temperature of the cold rolled sheet is It was set as the manufacturing method of the aluminum alloy fin material for heat exchangers characterized by being 120 degrees C or less.

  The present invention provides a heat exchanger according to claim 6, wherein the aluminum alloy fin material according to any one of claims 1 to 3 is assembled by brazing.

  This invention is the manufacturing method of the heat exchanger of Claim 6 in Claim 7, Comprising: The aluminum alloy fin material as described in any one of Claims 1-3 is combined with another member, This is 590. It is a method of performing brazing addition heat for 2 to 6 minutes at an ultimate temperature of ˜615 ° C., wherein the recrystallization temperature in the temperature raising process during brazing is 450 ° C. or less, and the temperature rise rate in the temperature range of 300 to 580 ° C. is 60 It was set as the manufacturing method of the heat exchanger characterized by setting it to -160 degreeC / min.

  According to the present invention, there is provided an aluminum alloy fin material for a heat exchanger that exhibits excellent resistance to fin melting at the time of brazing and exhibits excellent high-temperature durability after brazing, and an automotive heat exchanger using the same. Provided. Since the aluminum alloy fin material according to the present invention is excellent in formability, corrosion resistance after brazing addition heat, and thermal conductivity, it is suitably used as a fin material for heat exchangers for automobiles and the like.

  A preferred embodiment of an aluminum alloy fin material according to the present invention, a method for producing the same, and a heat exchanger using the aluminum alloy fin material will be described in detail.

1. Structure of Aluminum Alloy Fin Material and Brazing Supply Method The aluminum alloy fin material for heat exchanger according to the present invention (hereinafter simply referred to as “aluminum alloy fin material”) has a single layer structure that does not clad a skin material such as a brazing material. It is assumed that it is a bare material. The brazing necessary for brazing is supplied, for example, by clad a low-melting point Al—Si alloy on a flow path forming component that is a mating material.

2. Alloy Components The aluminum alloy fin material according to the present invention has Si: 0.70 to 1.50 mass% (hereinafter simply referred to as “%”), Fe: 0.05 to 2.00%, Mn: 1.0 to An aluminum alloy containing 2.0% and Zn: 0.5 to 4.0% as essential elements, and the balance being Al and inevitable impurities is used. Moreover, this aluminum alloy has Cu: 0.05 to 0.30%, Ti: 0.05 to 0.30%, Zr: 0.05 to 0.30%, Cr: 0.05 to 0.30% And V: You may further contain 1 type, or 2 or more types selected from 0.05 to 0.30% as a selective addition element. Furthermore, in addition to the above essential elements and selective additive elements, Ni, Co, etc. may be contained in amounts of 0.05% or less, and 0.15% in total as unavoidable impurities. Below, each component is demonstrated in detail.

Si
Si forms an intermetallic compound of Al—Fe—Si, Al—Mn—Si, and Al—Fe—Mn—Si together with Fe and Mn, and improves strength by dispersion strengthening, or an aluminum matrix Strengthen the solid solution by solid solution strengthening. Si content is 0.70 to 1.50%. If the content is less than 0.70%, the above effect is insufficient, and if it exceeds 1.50%, the melting point is lowered and the possibility of melting is increased. The preferable content of Si is 0.75 to 1.20%.

Fe
Fe forms an Al—Fe—Mn—Si based intermetallic compound together with Si and Mn, and improves the strength by dispersion strengthening. The content of Fe is 0.05 to 2.00%. If it is less than 0.05%, high-purity aluminum ingots must be used, resulting in high costs. On the other hand, if it exceeds 2.00%, a giant intermetallic compound is easily formed during casting, and the plastic workability is lowered. The preferable content of Fe is 0.10 to 1.50%.

Mn
Mn forms an Al—Mn—Si intermetallic compound together with Si, and an Al—Mn—Fe—Si intermetallic compound together with Si and Fe to improve the strength by dispersion strengthening, or an aluminum matrix. Strengthened by solid solution in the phase and solid solution strengthening. Mn content is 1.0 to 2.0%. If the content is less than 1.0%, the above effect is insufficient. If the content exceeds 2.0%, a giant intermetallic compound is easily formed during casting, and the plastic workability is lowered. The preferable content of Mn is 1.1 to 1.8%.

Zn
Zn can reduce the pitting corrosion potential, and by forming a potential difference with a brazed counterpart material such as a tube, the corrosion resistance of the counterpart material can be improved due to the sacrificial anticorrosive effect. The Zn content is 0.5 to 4.0%. If it is less than 0.5%, the effect of improving the corrosion resistance due to the sacrificial anticorrosive effect cannot be sufficiently obtained. On the other hand, if it exceeds 4.0%, the corrosion rate of the fin increases and disappears early, resulting in insufficient corrosion resistance. The preferable content of Zn is 1.0 to 3.5%.

Cu
Since Cu improves strength by solid solution strengthening, Cu may be contained. The Cu content is 0.05 to 0.30%. If it is less than 0.05%, the above effect is insufficient, and if it exceeds 0.30%, the pitting potential becomes noble and the sacrificial anticorrosive effect becomes insufficient. The preferable content of Cu is 0.10 to 0.30%.

Ti
Ti may be contained because it improves the strength by solid solution strengthening. Ti content is 0.05 to 0.30%. If it is less than 0.05%, the above effect is insufficient. If it exceeds 0.30%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The preferable content of Ti is 0.10 to 0.20%.

Zr
Zr may be included because it has the effect of improving strength by solid solution strengthening and precipitating Al—Zr-based intermetallic compounds to coarsen the crystal grains after heat of brazing addition. The Zr content is 0.05 to 0.30%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.30%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The preferable content of Zr is 0.10 to 0.20%.

Cr
Cr has the effect of improving strength by solid solution strengthening and precipitating Al—Cr intermetallic compounds to coarsen the crystal grains after brazing addition heat. The Cr content is 0.05 to 0.30%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.30%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. The preferable content of Cr is 0.10 to 0.20%.

V
V improves the strength by solid solution strengthening and also improves the corrosion resistance. V content is 0.05 to 0.30%. If it is less than 0.05%, the above effect cannot be obtained. If it exceeds 0.30%, it becomes easy to form a giant intermetallic compound, and the plastic workability is lowered. A preferable content of V is 0.10 to 0.20%.

  These Cu, Ti, Zr, Cr, and V may be added at least one type as necessary.

3. Solid solution amount before brazing and after brazing In the aluminum alloy fin material according to the present invention, the amount of solid solution Si before brazing addition heat is limited to 0.60% or less, and the amount of solid solution Mn is limited to 0.60% or less. . These limitations are intended to prevent fin melting during brazing heat and improve high temperature durability after brazing heat. The reason for this limitation will be described below.

  As already described, during brazing, a large amount of Si diffuses from the molten brazing to the crystal grain boundary of the fin material, and the melting point at the crystal grain boundary of the fin material is lowered. Since it is impossible to eliminate the diffusion of Si at the time of brazing, it is important to reduce solute Si in advance in the fin material before brazing. If the amount of solute Si before brazing is 0.60% or less, even if a large amount of Si diffuses from the molten braze to the crystal grain boundaries of the fin material, the total Si concentration at the crystal grain boundaries is below a predetermined level. Since it can suppress, the fall of melting | fusing point of the crystal grain boundary at the time of brazing can be suppressed, and melting | fusing of a crystal grain boundary can be prevented. On the other hand, if the amount of solid solution Si before brazing exceeds 0.60%, when a large amount of Si diffuses from the melt brazing to the crystal grain boundaries of the fin material, the total Si concentration at the crystal grain boundaries exceeds a predetermined level. The melting point of the crystal grain boundary at the time of brazing is lowered, and the crystal grain boundary is melted. Therefore, the amount of solute Si before brazing is restricted to 0.60% or less, preferably 0.55% or less. In addition, from the viewpoint of melting at the time of brazing, the lower limit value of the solute Si amount before brazing is not limited, but within the range of the Si content defined in the present invention, 0.05% or less It is difficult to do.

  On the other hand, as already described, for example, when used as a fin of a radiator, the cooling water flowing inside the tube becomes a high temperature of about 85 to 120 ° C., and the tube is repeatedly swollen by the internal pressure, and the fin has a high temperature repeatedly. Fatigue damage is given. However, at high temperatures, a phenomenon is observed in which part of the applied fatigue damage is recovered. As a result of intensive studies, the present inventors have revealed that solute Mn is a factor that hinders this recovery. And based on this fact, it discovered that high temperature durability could be improved by suppressing the amount of solid solution Mn after brazing addition heat low.

  Specifically, if the amount of dissolved Mn after the heat of brazing is 0.60% or less, the fatigue damage is sufficiently recovered and excellent high temperature durability can be obtained. If the amount of dissolved Mn after brazing exceeds 0.60%, recovery from fatigue damage is hindered and high-temperature durability becomes insufficient. Therefore, the amount of solute Mn after brazing is regulated to 0.60% or less, preferably 0.55% or less.

  During brazing, solid solution of Al-Mn-Si, Al-Fe-Mn-Si, and Al-Mn intermetallic compounds occurs, so the amount of solid solution Mn after brazing is higher than before brazing. To do. Therefore, in the state before brazing, the solid solution Mn content in the state after brazing cannot be 0.60% or less unless the solid solution Mn content is at least 0.60% or less. Therefore, the amount of dissolved Mn before brazing is also restricted to 0.60% or less. Thereby, excellent high temperature durability is exhibited. On the other hand, if the amount of solid solution Mn before brazing exceeds 0.60%, the amount of solid solution Mn after brazing cannot be suppressed to 0.60% or less, and excellent high-temperature durability is achieved. I can't get it. As described above, the amount of dissolved Mn before and after brazing is restricted to 0.60% or less, preferably 0.55% or less. From the viewpoint of high temperature durability, the lower limit of the amount of dissolved Mn before brazing and after brazing is not limited, but within the range of Mn content defined in the present invention, 0.05% % Or less is difficult.

4). Grain boundary segregation after brazing In the aluminum alloy fin material according to the present invention, at the time of brazing, the concentration of Si and Zn in the vicinity of the grain boundary is S1% and Z1%, respectively, and the concentration of Si and Zn in the matrix is S2%, respectively. , Z2%, the values of S1 / S2 and Z1 / Z2 are both specified to be 1.20 or less. This limitation is intended to prevent fin melting during brazing. The reason for this limitation will be described below.

  At the time of brazing, recrystallization occurs in the aluminum alloy fin material. As already described, since Zn and Si are segregated in the crystal grain boundary, the concentration of Zn and Si is higher in the vicinity of the crystal grain boundary and the melting point is lower than in the matrix. Therefore, in order to suppress melting of the fins, it is necessary to suppress grain boundary segregation during brazing.

  As a result of intensive studies, the present inventors have determined that the solid solution Zn content ratio and the solid solution Si content ratio between the vicinity of the grain boundary and the matrix after brazing, that is, the Si and Zn concentrations in the vicinity of the grain boundary are S1%, When the values of S1 / S2 and Z1 / Z2 are both 1.20 or less when the concentration of Si and Zn in the matrix is S2% and Z2%, respectively, It has been found that melting can be suppressed. When the values of S1 / S2 and Z1 / Z2 are both 1.20 or less, grain boundary segregation during brazing is sufficiently suppressed, and no melting of crystal grain boundaries occurs. On the other hand, when the value of either one or both of S1 / S2 and Z1 / Z2 exceeds 1.20, the suppression of grain boundary segregation during brazing is insufficient, and the melting of crystal grain boundaries occurs. End up. Preferred values of S1 / S2 and Z1 / Z2 are both 1.10 or less. Further, from the viewpoint of fin melting, the lower limit values of S1 / S2 and Z1 / Z2 are not limited. However, if the amount of solid solution elements in the vicinity of the grain boundary is too low with respect to the matrix, the elements of the matrix become grain boundaries. Therefore, it is difficult to set S1 / S2 and Z1 / Z2 to 0.50 or less, respectively.

  In the brazing cooling process, precipitation occurs preferentially in the vicinity of the grain boundary, and the amount of solid solution in the vicinity of the grain boundary decreases. Therefore, even if grain boundary segregation occurs during brazing, the solid solution amount of the grain boundary may be less than the solid solution amount of the matrix after brazing, and S1 / S2 and Z1 / Z2 May be less than 1.00. Further, the solid solution amount in the vicinity of the grain boundary here means an average value of the solid solution amount within a range of 0.05 μm on both sides from the grain boundary.

5. Recrystallization temperature at the time of brazing In the aluminum alloy fin material according to the present invention, the recrystallization temperature in the temperature raising process at the time of brazing is regulated to 450 ° C. or less. This limitation is intended to prevent fin melting during brazing. The reason for this limitation will be described below.

  As already described, in order to prevent melting of the crystal grain boundaries during brazing, it is necessary to suppress grain boundary segregation during recrystallization during brazing. However, as long as a certain amount of Si or Zn is dissolved in the matrix, it is difficult to completely eliminate the grain boundary segregation that occurs during recrystallization. Here, even if grain boundary segregation occurs, there is sufficient time from recrystallization during brazing to melting of the brazing material, and during this time, the elements segregated at the grain boundaries diffuse into the matrix. If the boundary segregation is eliminated, the crystal grain boundary does not melt. As a result of intensive studies focusing on this, the present inventors have completed recrystallization in the temperature rising process during brazing at an early stage, thereby eliminating grain boundary segregation before the solder melts. The inventors have found that melting of crystal grain boundaries can be suppressed.

  Specifically, it has been found that if the recrystallization temperature in the temperature raising process during brazing is 450 ° C. or less, the grain boundary segregation is eliminated by the melting of the brazing, and the crystal grain boundary does not melt. That is, when the recrystallization temperature in the temperature rising process during brazing is 450 ° C. or lower, the values of S1 / S2 and Z1 / Z2 can both be controlled to 1.20 or lower. Grain boundary segregation is sufficiently suppressed and melting of the crystal grain boundaries does not occur. On the other hand, when the recrystallization temperature in the temperature rising process at the time of brazing exceeds 450 ° C., the grain boundary segregation is not eliminated by the melting of the brazing, and the crystal grain boundaries are melted. That is, when the recrystallization temperature in the temperature rising process at the time of brazing exceeds 450 ° C., one or both of the above-mentioned S1 / S2 and Z1 / Z2 exceed 1.20. Suppression of grain boundary segregation during attachment is insufficient, and crystal grain boundaries are melted. The recrystallization temperature in the temperature raising process during brazing is preferably 400 ° C. or lower. From the viewpoint of resistance to fin melting, the lower limit of the recrystallization temperature in the temperature raising process during brazing is not limited. However, in the aluminum alloy fin material of the present invention, recrystallization occurs in a temperature range that is too low. Since the heat energy for making it become inadequate, it is difficult to set it as 250 degrees C or less.

  The brazing heat addition condition (corresponding to the brazing heat addition condition) is not particularly limited, but the heating rate in the temperature range of 300 to 580 ° C. is usually 60 to 160 ° C./min, preferably 80 to 140 ° C. / Min, and the ultimate temperature is 585 to 620 ° C. for 2 to 10 minutes, preferably the ultimate temperature is 590 to 615 ° C. for 2 to 6 minutes. When the temperature increase rate in the temperature range of 300 to 580 ° C. is less than 60 ° C./min, the temperature increase rate is too slow and the production efficiency is significantly impaired. On the other hand, when this rate of temperature rise exceeds 160 ° C./min, the temperature distribution during brazing may be non-uniform. Further, when the ultimate temperature is less than 585 ° C., the melting of the brazing may be insufficient and good brazing may not be obtained, and when it exceeds 620 ° C., the material may be melted. In addition, what was brazed is normally cooled at the cooling rate of 20-500 degreeC / min.

6). Manufacturing method of aluminum alloy fin material The aluminum alloy fin material according to the present invention can be manufactured by two different manufacturing methods. The manufacturing method of the first aspect has a feature in the hot rolling process and the cold rolling process, the hot rolling process is different from the second aspect described later, and further, the homogenization treatment process is an optional process, The conditions are also different from the second mode. On the other hand, the production method of the second aspect is characterized by a homogenization treatment process and a cold rolling process, and is different from the first aspect in that the homogenization treatment process is an essential process, and the conditions are also the first aspect. Is different. Furthermore, in the manufacturing method of the second aspect, the hot rolling step is different from that of the first aspect.

6-1. First, the manufacturing method of the first aspect of the aluminum alloy fin material according to the present invention will be described.

6-1-1. Each manufacturing process The manufacturing method of the 1st aspect of the aluminum alloy fin material which concerns on this invention is the process of casting an aluminum alloy, the hot rolling process of hot-rolling the cast ingot, and cold-rolling a hot-rolled sheet A cold rolling step for rolling, and one or more annealing steps for annealing the cold rolled sheet in one or both of the cold rolling step and one or both after the cold rolling step.

  The aluminum alloy fin material of the present invention realizes excellent fin melting resistance and high temperature durability by controlling the amount of solid solution Si and solid solution Mn, and the recrystallization temperature during brazing. . As a result of intensive studies, the inventors have the hot rolling process that has the largest effect on the solute Si content and solute Mn content in the manufacturing process, and the effect on the recrystallization temperature during brazing is the most. It has been found that the larger is the cold rolling process. Below, the control method of these hot rolling processes and cold rolling processes is demonstrated.

6-2. Hot Rolling Process The first aspect of the method for producing an aluminum alloy fin material according to the present invention is characterized by a hot rolling process in which a cast aluminum alloy ingot is hot rolled. The hot rolling process includes a heating stage for heating the ingot, a holding stage following the heating stage, and a hot rolling stage for rolling the heated and held ingot. In the heating stage, the rate of temperature increase from the time when reaching 400 ° C. to the time when the holding temperature is reached in the holding stage is regulated to 60 ° C./h or less. In the holding stage, the holding temperature is set to 450 to 560 ° C. and the holding time is set to 0.5 hour or more. Furthermore, in the hot rolling stage, the time during which the temperature of the hot rolled sheet is 400 ° C. or higher is specified to be 5 minutes or longer. By defining the conditions of the hot rolling process of the aluminum alloy in this way, the aluminum alloy fin material according to the present invention will be defined by the solid solution Si amount before brazing as defined by the present invention, as well as by the present invention. The amount of solid solution Mn before brazing and after brazing (hereinafter referred to as “the amount of solid solution Si and the amount of solid solution Mn defined in the present invention”) can be achieved, and excellent fin melt resistance during brazing And high temperature durability. The reason for this will be described below.

  In the aluminum alloy casting process, a large amount of Si and Mn are dissolved in the ingot matrix. A large amount of Si and Mn dissolved in the matrix in this way forms nuclei of Al-Mn-based and Al-Mn-Si-based intermetallic compounds in the heating stage before the rolling stage in the hot rolling process. Based on these nuclei, a large amount of the intermetallic compound is precipitated in the rolling stage. As a result, the hot rolling process including the heating step almost determines the solute Si amount and solute Mn amount of the aluminum alloy fin material defined in the present invention.

  Therefore, in order to reduce the amount of solute Si and the amount of solute Mn, in this heating stage, as many nuclei of Al—Mn and Al—Mn—Si intermetallic compounds as possible are generated, and in the rolling stage. It is sufficient to deposit as much as possible. In particular, since the amount of nucleation after reaching 400 ° C. in the heating stage increases, temperature control after this is important. The heating rate from reaching 400 ° C. to reaching the holding temperature in the heating stage is 60 ° C./h or less, and in the holding stage, the holding time is 450 to 560 ° C. and the holding time is 0.5 hours or more, In the hot rolling stage, by setting the time during which the temperature of the hot rolled sheet is 400 ° C. or more to 5 minutes or more, an Al—Mn based or Al—Mn—Si based intermetallic compound is sufficiently precipitated. The solute Si amount and the solute Mn amount specified in the invention can be obtained.

  When the heating rate from reaching 400 ° C. in the heating stage to reaching the holding temperature exceeds 60 ° C./h, or in the holding stage, the holding time at 450 to 560 ° C. is less than 0.5 hours. In this case, the amount of nuclei produced is insufficient, and the solid solution Si amount and the solid solution Mn amount specified in the present invention cannot be obtained. In addition, when the time during which the temperature of the hot-rolled sheet is 400 ° C. or more is less than 5 minutes in the rolling stage, the precipitation amount of the Al—Mn-based or Al—Mn—Si-based intermetallic compound is insufficient, The solute Si amount and solute Mn amount specified in the present invention cannot be obtained. When the holding temperature in the holding stage exceeds 560 ° C., the nucleus of the generated intermetallic compound is re-dissolved, and the solid solution Si amount and the solid solution Mn amount specified in the present invention cannot be obtained. Furthermore, when the holding temperature exceeds 560 ° C., melting occurs in the aluminum alloy, and there is a possibility that the fin material cannot be manufactured. Further, when the holding temperature in the holding stage is less than 450 ° C., the plastic workability during hot rolling becomes insufficient, and cracks may occur during hot rolling, making it impossible to produce an aluminum alloy material.

  The heating rate from reaching 400 ° C. until reaching the holding temperature in the heating stage is preferably 50 ° C./h or less, and the holding time in the holding stage is preferably 1.0 hour or more, and in the holding stage. The holding temperature is preferably 460 to 540 ° C., and the time during which the temperature of the hot rolled sheet is 400 ° C. or higher in the hot rolling stage is preferably 7 minutes or longer.

  From the viewpoint of the amount of solute Si and the amount of solute Mn specified in the present invention, the lower limit of the rate of temperature increase from when reaching 400 ° C. until reaching the holding temperature in the holding stage is not particularly limited. If it is less than ° C./h, it takes a very long time to raise the temperature, and the economy is significantly impaired. Moreover, from the viewpoint of the amount of solute Si and the amount of solute Mn specified in the present invention, the upper limit value of the holding time in the holding stage is not particularly limited, but if it exceeds 20 hours, the economic efficiency is significantly impaired. It is. Furthermore, the upper limit of the time during which the temperature of the hot-rolled sheet is 400 ° C. or higher in the hot rolling stage is not particularly limited, but if it exceeds 50 minutes, the economy is significantly impaired. It becomes.

6-3. Cold rolling process The manufacturing method of the first aspect of the aluminum alloy fin material according to the present invention further has a feature in the cold rolling process. In this cold rolling process, the temperature of the cold rolled sheet is regulated to 120 ° C. or lower. This control makes it possible to lower the recrystallization temperature during brazing, thereby reducing the recrystallization temperature in the temperature rising process during brazing addition heat to 450 ° C. or less. Grain boundary segregation is eliminated before melting, and as a result, the values of S1 / S2 and Z1 / Z2 are both 1.20 or less, and fin melting can be suppressed. The reason for this will be described below.

  As already described, recrystallization occurs in the aluminum alloy fin material during brazing, and the driving force for this recrystallization is the processing strain applied to the aluminum alloy during cold rolling. However, since heat is generated by processing even during cold rolling, simply performing cold rolling increases the material temperature due to this processing heat generation and recovers the applied processing strain. Can't get. As a result of intensive studies focusing on this, the present inventors have obtained a sufficient work strain if the temperature of the cold-rolled sheet during the cold-rolling process is 120 ° C. or less. It has been found that the recrystallization temperature can be lowered to 450 ° C. or lower.

  When the temperature of the cold-rolled sheet during cold rolling exceeds 120 ° C, the applied processing strain is recovered, and the recrystallization temperature during brazing cannot be lowered to 450 ° C or lower. The temperature of the cold rolled sheet during the cold rolling is preferably 100 ° C. or lower. From the viewpoint of processing strain, the lower limit value of the temperature of the aluminum alloy during cold rolling is not limited, but it is difficult to reduce the heat generation to 60 ° C. or less because the processing heat generation cannot be completely eliminated. is there. The method for controlling the temperature of the aluminum alloy during the cold rolling is not particularly limited. For example, the temperature is controlled by a method of measuring the temperature at the cold rolling outlet and feeding it back to the cold rolling speed. can do.

  In addition, what is necessary is just to perform the said temperature control by the last cold rolling after performing the last annealing, when performing the annealing process of 1 time or 2 times or more in the middle of cold rolling.

6-4. Other Steps The casting step in the first aspect of the aluminum alloy fin material according to the present invention is based on a semi-continuous casting (DC) method. As already described, the aluminum alloy fin material according to the present invention suppresses fin rupture due to fin melting and high-temperature fatigue by the heating stage, holding stage, and hot rolling stage in the hot rolling process. As a method of casting an aluminum alloy, there is a continuous casting method in addition to a semi-continuous casting method, but the aluminum alloy obtained by the continuous casting method has a thin plate thickness and cannot be used in a hot rolling process. I can't do it.

  The ingot obtained by casting the aluminum alloy may be subjected to a homogenization treatment step before the hot rolling step. The homogenization treatment step is usually preferably performed at 450 to 620 ° C. for 1 to 24 hours, and more preferably at 480 to 620 ° C. for 1 to 20 hours. If the treatment temperature is less than 450 ° C. or the treatment time is less than 1 hour, the homogenizing effect may not be sufficient, and if it exceeds 620 ° C., the ingot may be melted. Further, if the treatment time exceeds 24 hours, the economy is remarkably impaired. In the heating stage of the homogenization treatment process, it is possible to perform the same control as defined in the heating stage of the hot rolling process already described. However, once the aluminum alloy is cooled after the homogenization treatment, the nuclei of the produced intermetallic compound disappear, and thus the same effect as the treatment in the heating stage of the hot rolling process cannot be obtained.

  The annealing process is performed once or more in the middle of the cold rolling process and / or after the cold rolling process for the purpose of improving formability. Specifically, (1) one or more intermediate annealings are performed during the cold rolling process, (2) the final annealing process is performed once after the cold rolling process, or (3) (1 ) And (2) are implemented. In this annealing step, it is preferable to hold the fin material at 200 to 450 ° C. for 1 to 10 hours. When the holding temperature is less than 200 ° C. and the holding time is less than 1 hour, the above effect may not be sufficient. When holding temperature exceeds 450 degreeC, when holding time exceeds 10 hours, economical efficiency will be impaired remarkably. More preferable annealing conditions are a temperature of 230 to 420 ° C. and a holding time of 1 to 8 hours. In addition, although the upper limit of the frequency | count of an annealing process is not specifically limited, In order to avoid the cost increase by the increase in the number of processes, it is preferable to set it as 3 times. Moreover, when performing annealing in the middle of cold rolling, from the viewpoint of the processing strain already described, the cold rolling rate from the last annealing to the final plate thickness is preferably 15% or more. .

6-2. Next, the manufacturing method of the 2nd aspect of the aluminum alloy fin material which concerns on this invention is demonstrated.

6-2-1. Each manufacturing process The manufacturing method of the 2nd aspect of the aluminum alloy fin material which concerns on this invention is the process of casting an aluminum alloy, the homogenization process process of homogenizing the cast ingot, and the ingot which homogenized process Annealing a cold-rolled sheet in one or both of a hot-rolling process for hot-rolling, a cold-rolling process for cold-rolling a hot-rolled sheet, and during the cold-rolling process and after the cold-rolling process Including one or more annealing steps.

  The aluminum alloy fin material of the present invention realizes excellent fin melting resistance and high temperature durability by controlling the amount of solid solution Si and solid solution Mn, and the recrystallization temperature during brazing. . As a result of intensive studies, the inventors have found that the homogenization treatment process has the largest effect on the amount of dissolved Si and the amount of dissolved Mn in the production process, and the effect on the recrystallization temperature during brazing is the largest. It has been found that the larger is the cold rolling process. Below, the control method of these homogenization process steps and cold rolling steps will be described.

6-2. Homogenization treatment step The method for producing the second aspect of the aluminum alloy fin material according to the present invention is characterized by a homogenization treatment step of homogenizing the cast aluminum alloy ingot. This homogenization treatment process includes a heating stage for heating the ingot, a holding stage following the heating stage, and a cooling stage for cooling the heated and held ingot. In the heating stage, the rate of temperature rise from reaching 400 ° C. until reaching the holding temperature in the holding stage is regulated to 60 ° C./h or less. In the holding stage, the holding temperature is 450 to 560 ° C., and the holding time is defined as 1.0 hour or more. Furthermore, in the cooling stage, the cooling rate until the temperature of the ingot reaches 400 ° C. is regulated to 60 ° C./h or less. By defining the conditions of the homogenization process of the aluminum alloy as described above, the aluminum alloy fin material according to the present invention will be defined by the solid solution Si amount before brazing defined by the present invention and the present invention. The amount of solid solution Mn before brazing and after brazing (hereinafter referred to as “the amount of solid solution Si and the amount of solid solution Mn defined in the present invention”) can be achieved, and excellent fin melt resistance during brazing And high temperature durability. The reason for this will be described below.

  In the aluminum alloy casting process, a large amount of Si and Mn are dissolved in the ingot matrix. Thus, a large amount of Si and Mn dissolved in the matrix generates Al-Mn-based and Al-Mn-Si-based intermetallic compounds in the heating stage, holding stage, and cooling stage in the homogenization treatment process. The conditions of the homogenization process consisting of these three stages substantially determine the solute Si amount and the solute Mn amount specified in the present invention of the aluminum alloy fin material before brazing.

  Therefore, in order to reduce the amount of solute Si and the amount of solute Mn, as much Al—Mn and Al—Mn—Si intermetallic compounds as possible are precipitated in this heating stage, holding stage and cooling stage. Just do it. In particular, since the amount of precipitation increases in a temperature region of 400 ° C. or higher, temperature control after this is important. The temperature rising rate from reaching 400 ° C. until reaching the holding temperature in the heating stage is set to 60 ° C./h or less. In the holding stage, the holding time is set to 450 to 560 ° C. In the present invention, the cooling rate until the temperature of the ingot reaches 400 ° C. is set to 60 ° C./h or less, so that Al—Mn-based and Al—Mn—Si-based intermetallic compounds are sufficiently precipitated. The solute Si amount and the solute Mn amount can be obtained.

  When the heating rate from reaching 400 ° C. to reaching the holding temperature exceeds 60 ° C./h in the heating stage, or when the holding temperature is less than 450 ° C. or holding time is less than 1.0 hour in the holding stage. When the cooling rate until the temperature of the ingot reaches 400 ° C. in the cooling stage exceeds 60 ° C./h, the amount of precipitated intermetallic compound is insufficient, and the solid solution defined in the present invention The amount of Si and the amount of solute Mn cannot be obtained. When the holding temperature in the holding stage exceeds 560 ° C., the precipitated intermetallic compound Si and Mn are re-dissolved, and the solid solution Si amount and the solid solution Mn amount specified in the present invention cannot be obtained. Furthermore, when the holding temperature exceeds 560 ° C., melting occurs in the aluminum alloy, and there is a possibility that the fin material cannot be manufactured.

  The heating rate from reaching 400 ° C. until reaching the holding temperature in the heating stage is preferably 50 ° C./h or less, and the holding time in the holding stage is preferably 2.0 hours or more. The holding temperature is preferably 480 to 530 ° C., and the cooling rate until the temperature of the ingot reaches 400 ° C. in the cooling stage is preferably 50 ° C./h or less.

  From the viewpoint of the amount of dissolved Si and the amount of dissolved Mn specified in the present invention, the rate of temperature increase from reaching 400 ° C. in the heating stage to the time when the holding temperature in the holding stage is reached, The lower limit of the cooling rate until the temperature reaches 400 ° C. is not particularly limited, but if it is less than 10 ° C./h, it takes a very long time to raise or lower the temperature, and the economy is extremely high. Damaged. Moreover, from the viewpoint of the amount of solute Si and the amount of solute Mn specified in the present invention, the upper limit value of the holding time in the holding stage is not particularly limited, but if it exceeds 20 hours, the economic efficiency is remarkably impaired. It is.

6-3. Cold rolling process The manufacturing method of the second aspect of the aluminum alloy fin material according to the present invention further has features in the cold rolling process. In this cold rolling process, the temperature of the cold rolled sheet is regulated to 120 ° C. or lower. This control makes it possible to lower the recrystallization temperature during brazing, thereby reducing the recrystallization temperature in the temperature rising process during brazing addition heat to 450 ° C. or lower, and as a result, melting of the brazing during brazing. Grain boundary segregation is eliminated before, and as a result, the values of S1 / S2 and Z1 / Z2 are both 1.20 or less, and the melting of fins can be suppressed. The reason for this will be described below.

  As already described, recrystallization occurs in the aluminum alloy fin material during brazing, and the driving force for this recrystallization is the processing strain applied to the aluminum alloy during cold rolling. However, since heat is generated by processing even during cold rolling, simply performing cold rolling increases the material temperature due to this processing heat generation and recovers the applied processing strain. Can't get. As a result of intensive studies focusing on this, the present inventors have obtained a sufficient work strain if the temperature of the cold-rolled sheet during the cold-rolling process is 120 ° C. or less. It has been found that the recrystallization temperature can be lowered to 450 ° C. or lower.

  When the temperature of the cold-rolled sheet during cold rolling exceeds 120 ° C, the applied processing strain is recovered, and the recrystallization temperature during brazing cannot be lowered to 450 ° C or lower. The temperature of the cold rolled sheet during the cold rolling is preferably 100 ° C. or lower. From the viewpoint of processing strain, the lower limit value of the temperature of the aluminum alloy during cold rolling is not limited, but it is difficult to reduce the heat generation to 60 ° C. or less because the processing heat generation cannot be completely eliminated. is there. The method for controlling the temperature of the aluminum alloy during the cold rolling is not particularly limited. For example, the temperature is controlled by a method of measuring the temperature at the cold rolling outlet and feeding it back to the cold rolling speed. can do.

  In addition, what is necessary is just to perform the said temperature control by the last cold rolling after performing the last annealing, when performing the annealing process of 1 time or 2 times or more in the middle of cold rolling.

6-4. Other Steps The casting step in the second aspect of the aluminum alloy fin material according to the present invention is based on a semi-continuous casting (DC) method. As described above, the aluminum alloy fin material according to the present invention suppresses fin rupture due to fin melting and high-temperature fatigue by the heating stage, holding stage, and cooling stage in the homogenization process. As a method of casting an aluminum alloy, there is a continuous casting method in addition to a semi-continuous casting method, but the aluminum alloy obtained by the continuous casting method has a thin plate thickness and cannot be used in a hot rolling process. I can't do it.

  After the casting process, the aluminum alloy ingot subjected to the homogenization treatment process is then subjected to a hot rolling process. In the heating stage in the hot rolling step, the ingot is preferably heated at 400 to 580 ° C for 0.5 hour or longer, more preferably 420 to 550 ° C for 1 hour or longer. When the heating temperature is less than 400 ° C., the plastic workability is low, and cracking may occur during hot rolling. When the heating temperature exceeds 580 ° C., the ingot may be melted, and the heating time is 0. If the time is less than 5 hours, the temperature of the ingot may not be uniform. In addition, although the upper limit of heating time is not specifically limited, it is about 20 hours in this invention from a viewpoint of economical efficiency.

  The annealing process is performed once or more in the middle of the cold rolling process and / or after the cold rolling process for the purpose of improving formability. Specifically, (1) one or more intermediate annealings are performed during the cold rolling process, (2) the final annealing process is performed once after the cold rolling process, or (3) (1 ) And (2) are implemented. In this annealing step, it is preferable to hold the fin material at 200 to 450 ° C. for 1 to 10 hours. When the holding temperature is less than 200 ° C. and the holding time is less than 1 hour, the above effect may not be sufficient. When holding temperature exceeds 450 degreeC, when holding time exceeds 10 hours, economical efficiency will be impaired remarkably. More preferable annealing conditions are a temperature of 230 to 420 ° C. and a holding time of 1 to 8 hours. In addition, although the upper limit of the frequency | count of an annealing process is not specifically limited, In order to avoid the cost increase by the increase in the number of processes, it is preferable to set it as 3 times. Moreover, when performing annealing in the middle of cold rolling, from the viewpoint of the processing strain already described, the cold rolling rate from the last annealing to the final plate thickness is preferably 15% or more. .

  The plate thickness of the aluminum alloy fin material according to the present invention is not particularly limited, but when it is a thin material having a thickness of 100 μm or less, the advantages of improvement in melting resistance and improvement in high temperature durability are sufficiently exhibited. The When the plate thickness is larger than 100 μm, the melting of fins and high-temperature durability do not matter so much, and the superiority of the present invention is not sufficiently exhibited.

7). Heat exchanger The aluminum alloy fin material according to the present invention is preferably used as a fin for a heat exchanger. For example, after corrugating into a fin shape, the heat exchanger can be obtained by combining with heat exchanger members such as flow path forming parts and header plates, and subjecting it to brazing additional heat.

  The heat exchanger is assembled by disposing a fin material on the outer surface of the flow path forming component having both end portions attached to the header plate. Next, the overlapping portions on both ends of the flow path forming component, the fin material and the outer surface of the flow path forming component, and both ends of the flow path forming component and the header plate are simultaneously joined by one brazing heating. As the brazing method, a flux-free brazing method, a nocolok brazing method, or a vacuum brazing method is used, but the nocolock brazing method is preferable. In such brazing, as described above, the recrystallization temperature in the temperature rising process during brazing is set to 450 ° C. or lower in order to prevent fin melting during brazing. Other brazing heat addition conditions are preferably as described above.

  Next, the present invention will be described in more detail based on examples of the present invention and comparative examples, but the present invention is not limited to these.

Example 1 (Invention Examples 1-1 to 1-9, 1-19 to 1-28, Comparative Examples 1-10 to 1-18, 1-29 to 1-34)
First, the aluminum alloy fin material manufactured by the manufacturing method of the first aspect will be described.
Each aluminum alloy having the alloy composition shown in Table 1 was cast by DC casting, and each side was chamfered and finished. The thickness of the ingot after chamfering was 400 mm in all cases. These aluminum alloy ingots were subjected to a homogenization treatment step, a hot rolling step, a cold rolling step, and an annealing step under the conditions shown in Table 2. The plate thickness after hot rolling was 3 mm in all cases. Then, (1) cold rolling → intermediate annealing → final cold rolling order, (2) cold rolling → intermediate annealing → final cold rolling → final annealing order, (3) cold rolling → final annealing order In either case, a fin material sample having a final thickness of 0.05 mm was produced. The conditions for the intermediate annealing and the final annealing were both 2 hours at 370 ° C., and the rolling ratio in the final cold rolling after the intermediate annealing was 30%. Table 2 shows the process combinations.

  No problems occur in the above manufacturing process, and if it can be rolled to a final plate thickness of 0.05 mm, the manufacturability is set to “◯”, and cracking occurs during casting or rolling to roll to a final plate thickness of 0.05 mm In the case where the fin material could not be manufactured due to the failure or the melting during the homogenization process, Table 3 shows the manufacturability as “x”.

  The said fin material sample was used for each following evaluation. Table 4 shows the conditions for brazing heat addition during the evaluation (corresponding conditions for brazing heat addition), and Table 3 shows the evaluation results. In addition, since the sample was not able to be manufactured for those having the productivity “x” in Table 3, the following evaluation could not be performed.

(Evaluation of brazing)
Each fin material sample was corrugated to form heat exchanger fins. This fin is combined with a brazing material surface of a tube equivalent material having a plate thickness of 0.3 mm obtained by clad 10% A4045 alloy on an A3003 alloy core material, and immersed in a 5% fluoride flux aqueous solution. A mini-core sample was prepared by subjecting it to brazing heat. In this mini-core sample, the case where the fin was not melted was judged as acceptable (O), and the case where the fin was melted was judged as unacceptable (x).

(Measurement of tensile strength after brazing heat)
The fin material sample alone was subjected to brazing equivalent heating under any of the conditions in Table 4, and subjected to a tensile test according to JIS Z2241 under the conditions of a tensile speed of 10 mm / min and a gauge length of 50 mm. The tensile strength was read from the obtained stress-strain curve. As a result, the case where the tensile strength was 130 MPa or more was determined to be acceptable (◯), and the case where the tensile strength was less than that was rejected (x).

(Measurement of high temperature fatigue life after brazing heat)
The fin material sample alone was subjected to brazing equivalent heating under any of the conditions in Table 4 and subjected to a fatigue test in a constant temperature bath at a temperature of 100 ° C. according to JIS Z2273. The stress ratio was 0.1, the maximum stress was 100 MPa, and the frequency was 20 Hz. The case where the number of repetitions until breakage was 10 ⁶ times or more was regarded as acceptable (◯), and the number less than that was regarded as unacceptable (x).

(Measurement of solute Si amount and solute Mn amount)
The fin material sample alone was subjected to brazing equivalent heating under any of the conditions in Table 4. Measurements were made by subjecting brazing-equivalent heating to those not subjected to brazing as test samples, dissolving them in a phenol solution, removing undissolved intermetallic compounds by filtration, and subjecting them to emission analysis. About each of Si and Mn, what subtracted the quantity which existed as an intermetallic compound from content was calculated | required as a solid solution amount.

(Determination of recrystallization temperature during brazing heat)
A single fin material sample is heated under any of the conditions in Table 4, and is taken out when the temperature of the fin material sample reaches 450 ° C. in the course of temperature increase, and in accordance with JIS Z2241 under the conditions of a tensile speed of 10 mm / min and a gauge length of 50 mm. The sample was subjected to a tensile test. When 0.2% proof stress is read from the obtained stress-strain curve, and the value is 80 MPa or less, it is determined that recrystallization has been completed and passed (O), and when it exceeds 80 MPa It was determined that recrystallization was incomplete, and the result was rejected (x).

(Evaluation of grain boundary segregation)
The fin material sample alone was subjected to brazing equivalent heating under any of the conditions shown in Table 4. Samples subjected to brazing equivalent heating and those not subjected to brazing were used as test samples, and sampling was performed with a size of 20 μm × 20 μm so that the grain boundaries could enter by FIB (focused ion beam). And about this sample, the mapping of Si and Zn was performed in the visual field of 0.2 micrometer x 0.2 micrometer by the energy dispersive X ray analysis (EDS) using the transmission scanning electron microscope (STEM). As a result of this mapping, the average values of the semi-quantitative values of the Si and Zn concentrations in the range of 0.05 μm on both sides from the grain boundary were obtained and were designated as S1 and Z1, respectively. Moreover, the average value of the semi-quantitative values of the Si and Zn concentrations in the matrix was determined, and S2 and Z2, respectively, and the values of S1 / S2 and Z1 / Z2 were calculated.

(Evaluation of corrosion resistance by measuring corrosion depth)
A minicore sample similar to that used for brazing evaluation was prepared and subjected to the SWWAT test based on ASTM-G85. Those in which corrosion penetration did not occur in the tube equivalent material in 1000 hours were evaluated as acceptable (◯), and those in which corrosion penetration occurred were determined to be unacceptable (x).

  In Examples 1-1 to 1-9 and 1-19 to 1-28 of the present invention, the conditions specified in the present invention were satisfied, and manufacturability, brazing, tensile strength after brazing heat, brazing heat Both the high temperature fatigue life and the corrosion resistance later passed.

  On the other hand, in Comparative Example 1-10, since there was too little Si component, the tensile strength after brazing addition heat was disqualified.

  In Comparative Example 1-11, since there was too much Si component, the fin material melted during brazing, and the brazing property was unacceptable.

  In Comparative Example 1-12, since there were too many Fe components, a crack was produced during rolling, and the fin material could not be produced, and the productivity was unacceptable.

  In Comparative Example 1-13, since there was too little Mn component, the tensile strength after brazing addition heat was disqualified.

  In Comparative Example 1-14, since there was too much Mn component, the crack generate | occur | produced at the time of rolling, a fin material could not be manufactured, and productivity was unsuccessful.

  In Comparative Example 1-15, since there was too much Cu component, corrosion resistance was unacceptable.

  In Comparative Example 1-16, since there were too many Ti, Zr, Cr, and V components, cracking occurred during rolling, and the fin material could not be produced, and the productivity was unacceptable.

  In Comparative Example 1-17, since there was too little Zn component, corrosion resistance was unacceptable.

  In Comparative Example 1-18, since there was too much Zn component, corrosion resistance was unacceptable.

  In Comparative Example 1-29, in the heating stage of the hot rolling process, the rate of temperature increase from reaching 400 ° C. to reaching the holding temperature was too high, so that the amount of dissolved Si before and after brazing was too high during brazing. Melting occurred at the grain boundaries of the fin material and the brazing property was unacceptable, and the amount of Mn before and after brazing was too large, and the high temperature fatigue life was also unacceptable.

  In Comparative Example 1-30, since the holding temperature was too low in the holding stage of the hot rolling process, the amount of solid solution Si before and after brazing was too much and melting occurred at the grain boundaries of the fin material during brazing. In addition, the high-temperature fatigue life was also unacceptable due to the excessive amount of Mn before and after brazing.

  In Comparative Example 1-31, since the holding temperature was too high in the holding stage of the hot rolling process, the amount of solid solution Si before and after brazing was too much and melting occurred at the grain boundaries of the fin material during brazing. In addition, the high-temperature fatigue life was also unacceptable due to the excessive amount of Mn before and after brazing.

  In Comparative Example 1-32, since the holding time was too short in the holding stage of the hot rolling process, the amount of solute Si before and after brazing was too much, and melting occurred at the grain boundaries of the fin material during brazing. In addition, the high-temperature fatigue life was also unacceptable due to the excessive amount of Mn before and after brazing.

  In Comparative Example 1-33, in the hot rolling stage of the hot rolling process, since the time of 400 ° C. or higher was too short, the amount of solute Si before and after brazing was too large, and the grains of the fin material during brazing Melting occurred in the boundary and the brazing property was rejected, and the amount of Mn before and after brazing was too much, and the high temperature fatigue life was also rejected.

  In Comparative Example 1-34, the temperature of the cold rolled sheet was too high in the cold rolling process, so the recrystallization temperature during brazing exceeded 450 ° C., and as a result, the Si and Zn grains produced during brazing The segregation of the boundary was not eliminated, and the values of S1 / S2 and Z1 / Z2 were too high, and the brazing property was rejected due to melting at the grain boundaries of the fin material during brazing.

Second Example (Invention Examples 2-1 to 2-9, 2-19 to 2-26, Comparative Examples 2-10 to 2-18, 2-27 to 2-32)
Next, the aluminum alloy fin material manufactured by the manufacturing method of the second aspect will be described.
Aluminum alloys having the alloy compositions shown in Table 1 were cast by DC casting, and each side was chamfered and finished. The thickness of the ingot after chamfering was 400 mm in all cases. These aluminum alloy ingots were subjected to a homogenization treatment process, a hot rolling process, a cold rolling process, and an annealing process under the conditions shown in Table 5. The ingot that had been homogenized was heated at 480 ° C. for 3 hours in the heating stage of the hot rolling process, and then subjected to the hot rolling stage to obtain a hot rolled sheet having a thickness of 3 mm. Then, (1) cold rolling → intermediate annealing → final cold rolling order, (2) cold rolling → intermediate annealing → final cold rolling → final annealing order, (3) cold rolling → final annealing order In either case, a fin material sample having a final thickness of 0.05 mm was produced. The conditions for the intermediate annealing and the final annealing were both 2 hours at 370 ° C., and the rolling ratio in the final cold rolling after the intermediate annealing was 30%. Table 2 shows the process combinations.

  No problems occur in the above manufacturing process, and if it can be rolled to a final plate thickness of 0.05 mm, the manufacturability is set to “◯”, and cracking occurs during casting or rolling to roll to a final plate thickness of 0.05 mm Table 6 shows the manufacturability as “x” when the fin material could not be manufactured due to the inability to melt or melting during the homogenization process.

  The said fin material sample was used for each following evaluation. Table 4 shows the conditions of brazing heat applied during the evaluation (corresponding conditions for brazing heat addition), and Table 6 shows the evaluation results. In addition, since the sample was not able to be manufactured for those with the productivity “x” in Table 6, the following evaluation could not be performed.

  Brazing evaluation, measurement of tensile strength after brazing heat, measurement of high-temperature fatigue life after brazing heat, measurement of solute Si content and solute Mn content, determination of recrystallization temperature during brazing heat, The evaluation of grain boundary segregation and the corrosion resistance evaluation by measuring the corrosion depth were measured and evaluated in the same manner as in the first example.

  In Invention Examples 2-1 to 2-9 and 2-19 to 2-26, the conditions specified in the present invention are satisfied, and the manufacturability, brazing property, tensile strength after brazing heat, brazing heat Both the high temperature fatigue life and the corrosion resistance later passed.

  On the other hand, in Comparative Example 2-10, since there was too little Si component, the tensile strength after brazing addition heat was disqualified.

  In Comparative Example 2-11, since the Si component was too much, the fin material melted during brazing, and the brazing property was unacceptable.

  In Comparative Example 2-12, since there were too many Fe components, a crack was produced during rolling, and the fin material could not be produced, resulting in an unacceptable manufacturability.

  In Comparative Example 2-13, since there was too little Mn component, the tensile strength after brazing addition heat was disqualified.

  In Comparative Example 2-14, since the Mn component was too much, cracking occurred during rolling, and the fin material could not be produced, and the productivity was unacceptable.

  In Comparative Example 2-15, since there was too much Cu component, corrosion resistance was unacceptable.

  In Comparative Example 2-16, since there were too many Ti, Zr, Cr, and V components, cracking occurred during rolling, and the fin material could not be manufactured, and the productivity was unacceptable.

  In Comparative Example 2-17, since there was too little Zn component, corrosion resistance was unacceptable.

  In Comparative Example 2-18, since there was too much Zn component, corrosion resistance was unacceptable.

  In Comparative Example 2-27, in the heating stage of the homogenization treatment process, the rate of temperature increase from reaching 400 ° C. to reaching the holding temperature was too large, so the amount of solid solution Si before and after brazing, and before and after brazing The amount of solid solution Si was too high and melting occurred at the grain boundaries of the fin material at the time of brazing, and the brazing property was rejected. In addition, the amount of Mn before and after brazing was too large and the high temperature fatigue life was also rejected. It was.

  In Comparative Example 2-28, since the holding temperature was too low in the holding stage of the homogenization treatment process, the amount of solid solution Si before and after brazing was too much and melting occurred at the grain boundaries of the fin material during brazing. In addition, the high-temperature fatigue life was also unacceptable due to the excessive amount of Mn before and after brazing.

  In Comparative Example 2-29, since the holding temperature was too high in the holding stage of the homogenization treatment process, the amount of solid solution Si before and after brazing was too much and melting occurred at the grain boundaries of the fin material during brazing. In addition, the high-temperature fatigue life was also unacceptable due to the excessive amount of Mn before and after brazing.

  In Comparative Example 2-30, since the holding time was too short in the holding stage of the homogenization treatment process, the amount of solid solution Si before and after brazing was too much, and melting occurred at the grain boundaries of the fin material during brazing. In addition, the high-temperature fatigue life was also unacceptable due to the excessive amount of Mn before and after brazing.

  In Comparative Example 2-31, in the hot rolling stage of the homogenization treatment process, the cooling rate until the temperature of the ingot reached 400 ° C. was too high during the cooling stage, so the amount of solute Si before and after brazing was The amount of Mn before and after brazing was too much, and the high temperature fatigue life was also unacceptable.

  In Comparative Example 2-32, the temperature of the cold rolled sheet was too high in the cold rolling process, so the recrystallization temperature during brazing exceeded 450 ° C., and as a result, the Si and Zn grains produced during brazing The segregation of the boundary was not eliminated, and the values of S1 / S2 and Z1 / Z2 were too high, and the brazing property was rejected due to melting at the grain boundaries of the fin material during brazing.

  The aluminum alloy fin material according to the present invention is excellent in brazing properties such as strength, corrosion resistance, joining rate at the time of brazing, and melting resistance, and therefore is particularly suitably used as a fin for an automotive heat exchanger.

Claims (7)

  Si: 0.70-1.50 mass%, Fe: 0.05-2.00 mass%, Mn: 1.0-2.0 mass%, Zn: 0.5-4.0 mass%, the balance Al and It is made of an aluminum alloy composed of inevitable impurities, and has a solid solution Si amount of 0.60 mass% or less and a solid solution Mn amount of 0.60 mass% or less before brazing addition heat, and recrystallization in the temperature rising process during brazing addition heat An aluminum alloy fin material for heat exchangers, characterized in that the temperature is 450 ° C or lower.   In the aluminum alloy after the brazing heat, the solid solution Mn amount is 0.6 mass% or less, the Si and Zn concentrations in the vicinity of the grain boundary are S1 mass% and Z1 mass%, respectively, and the Si and Zn concentrations in the matrix are respectively The aluminum alloy fin material for a heat exchanger according to claim 1, wherein the values of S1 / S2 and Z1 / Z2 are all 1.20 or less when S2 mass% and Z2 mass% are set.   The aluminum alloy is Cu: 0.05 to 0.30 mass%, Ti: 0.05 to 0.30 mass%, Zr: 0.05 to 0.30 mass%, Cr: 0.05 to 0.30 mass%, and V The aluminum alloy fin material for a heat exchanger according to claim 1 or 2, further comprising one or more selected from 0.05 to 0.30 mass%.   It is a manufacturing method of the aluminum alloy fin material for heat exchangers as described in any one of Claims 1-3, Comprising: The process of casting the said aluminum alloy, The hot rolling process of hot-rolling the cast ingot, A cold rolling process for cold rolling the hot rolled sheet, and one or more annealing processes for annealing the cold rolled sheet in one or both of the cold rolling process and after the cold rolling process. The hot rolling process includes a heating stage, a holding stage, and a hot rolling stage, and in the heating stage, the rate of temperature increase from reaching 400 ° C. to reaching the holding temperature in the holding stage is 60 ° C./h or less. The holding temperature in the holding stage is 450 to 560 ° C. and the holding time is 0.5 hours or more. During the hot rolling stage, the time that the temperature of the hot rolled sheet is 400 ° C. or more is 5 minutes or more. In the cold rolling process, Method for producing a heat exchanger use aluminum alloy fin material, characterized in that the temperature of the rolled plate is 120 ° C. or less.   It is a manufacturing method of the aluminum alloy fin material for heat exchangers as described in any one of Claims 1-3, Comprising: The process of casting the said aluminum alloy, The homogenization process process of homogenizing the cast ingot, , One or both of a hot rolling process for hot rolling the homogenized ingot, a cold rolling process for cold rolling the hot rolled sheet, and during the cold rolling process and after the cold rolling process At least one annealing step for annealing the cold-rolled sheet, and the homogenization treatment step includes a heating step, a holding step, and a cooling step, and the holding step is held after reaching 400 ° C. in the heating step. The temperature rising rate until reaching the temperature is 60 ° C./h or less, the holding temperature in the holding stage is 450 to 560 ° C., the holding time is 1.0 hour or more, and the temperature of the ingot is in the cooling stage. Cooling speed to reach 400 ℃ There is less 60 ° C. / h, in the cold rolling step, the manufacturing method of the heat exchanger use aluminum alloy fin material, characterized in that the temperature of the cold-rolled sheet is 120 ° C. or less.   The aluminum alloy fin material as described in any one of Claims 1-3 is assembled | attached by brazing, The heat exchanger characterized by the above-mentioned.   It is a manufacturing method of the heat exchanger of Claim 6, Comprising: The aluminum alloy fin material as described in any one of Claims 1-3 is combined with another member, This is 2 at the ultimate temperature of 590-615 degreeC. A method of heating by brazing for 6 minutes, wherein the recrystallization temperature in the temperature raising process during brazing is 450 ° C. or less, and the temperature raising rate in the temperature range of 300 to 580 ° C. is 60 to 160 ° C./min. The manufacturing method of the heat exchanger characterized by these.